Distribution characteristics of microplastics in storm-drain inlet sediments affected by the types of urban functional areas, economic and demographic conditions in southern Beijing

A storm-drain inlet is an important link in the transport of microplastic pollutants in urban rainwater runoff. In three functional districts (agricultural, commercial, and residential) from Beijing South 2nd Ring Road to South 6th Ring Road, microplastics in storm-drain inlet sediments were analyzed for abundance and characteristics. The abundance of microplastics in the collected samples ranged from 1121 symbolscript 247 items symbolscript 1 to 7393 symbolscript 491 items symbolscript 1. Among the sample areas, the commercial area had the greatest abundance (11094 items symbolscript 1), while the agricultural area had the lowest (833 items symbolscript 1). The microplastics in the samples were mainly fragments, accounting for 50.4%. Microplastics of less than 1 mm accounted for 74.8%. The color of microplastics was diverse, with colored MPs accounting for 26% and transparent ones for 47.8%. Most of the polymers detected were PET, PS, and PP, which are the most commonly used polymers. Overall, the results provide baseline data on microplastic pollution and its associated risks, in addition to guidelines for controlling runoff pollution.

Automated summary

The abundance and characteristics of microplastics in storm-drain inlet sediments were analyzed in three functional districts (agricultural, commercial, and residential) from Beijing South 2nd Ring Road to South 6th Ring Road. The collected samples had a range of microplastic abundance from 1121 to 7393 items/m3. The commercial area had the highest abundance (11094 items/m3), while the agricultural area had the lowest (833 items/m3). The microplastics were mainly fragments, accounting for 50.4%, with microplastics of less than 1 mm accounting for 74.8%. The majority of detected polymers were PET, PS, and PP. Overall, these results provide baseline data and guidelines for controlling microplastic pollution in urban runoff.